The present invention relates to a stamped-steel wheel, especially for use on an automotive vehicle, provided with a recess for correct fixation of the wheel balance weight in order to achieve a dynamic counterbalance of the wheel-tire assembly, as well as a wheel rim and a wheel disc thus configured.
Conventional steel wheels comprise a rim and a disc associated with each other, the rim being responsible for fixing the tire to the wheel by means of two end regions or flanges that form a channel for fixing the tire. Alternatively, there may be a stamped-steel wheel, wherein the outer flange is an integral part of the disc. On any one of these types of wheel, these two end regions or flanges are protuberant and constitute the wheel region where the diameter is maximum. The flanges have a substantially curved xe2x80x9cxe2x80x9d-shaped profile with its free tip substantially perpendicular to the remainder of the flange body.
Beside serving as a tire guide, the flange enables one to affix wheel balance weights to the wheel so as to balance dynamically the wheel-tire assembly, enabling the vehicle equipped with the wheel to travel at a range of speeds without excessive vibration of the assembly. The balance weight comprises a body made of metal (as for example, lead or another high-density metal/alloy), from which a substantially xe2x80x9cUxe2x80x9d-shaped metallic fixation clamp projects, a first end of the clamp being associated with the metal body and a second end being free.
To fix the counterbalance weight on the wheel, the weight is positioned on the flange and forced to move against the wheel so that the opening of the xe2x80x9cUxe2x80x9d-shaped clamp engages the free end of the flange. As the weight is pressed against the wheel, the xe2x80x9cUxe2x80x9d-shaped clamp is forced open by the free end of the flange until the metallic body touches the outer surface of the flange body. The U-shaped clamp is resilient and thus applies a force on the tip of the flange because of its tendency to want to return to its normal undeformed shape, thus exerting a normal force component on the flange that causes friction between the clamp and the flange. Accordingly, the balance weight is fixed in position on the wheel, even when there is rotary motion of the wheel.
In the case of painted wheels, the friction coefficient presented by the surface of the flange tip is sufficient to provide sufficient friction force to maintain the balance weight correctly positioned, even if the vehicle equipped with the wheel runs at high speeds (which results in a high wheel rotational speed and thus a strong centrifugal force that tends to loosen the weight) and passes over obstacles on roads, such as holes or other unevenness/irregularities.
On the other hand, common wheels made of stamped steel have the drawback of being not particularly esthetically attractive, which is a factor that limits their penetration in the market, especially in the case of luxurious and expensive vehicles. With a view to eliminate this drawback, there have been developed steel wheels with a chromed finish, which significantly improves the wheels"" appearance, making them more desirable as original equipment or as after-market accessory items. However, the chromed finish of the wheel, and hence of the flange tip, causes a reduction in the friction coefficient of the surface of the flange on which the clamp of the counterbalance weight is fixed. This reduced friction coefficient proves insufficient to maintain the counterbalance weight in the desired position, even if it is fixed correctly by the above-described process. Thus, when the vehicle equipped with such chromed steel wheels runs at high speeds or passes over holes or other irregularities on the ground, the possibility of the wheel weight becoming loose is not negligible, which entails a significant drawback in using such wheels.
For the purpose of eliminating these drawbacks, U.S. Pat. No. 6,238,006 discloses a vehicle wheel rim having a flange provided with a recess for engaging the clamp of the balance weight. The recess comprises a shoulder, which engages a barb or projection formed on the balance weight clamp, such that a shape-locking engagement occurs between the clamp and the recess. Although the arrangement may eliminate the above-mentioned drawbacks, the arrangement requires a specially designed balance weight clamp provided with a locking projection configured to work with the particular recess shape. A conventional smooth-walled clamp would not work with the recess of the ""006 patent.
Another solution is proposed in U.S. Pat. No. 5,733,016, which discloses a wheel having a flange provided with a concave recess and a counterbalance weight whose clamp has a hemmed free end configured to fit into the recess in such a way that the balance weight will have greater adherence to the wheel. In this arrangement also, the balance weight clamp must be specially designed to work with the particular recess shape; a conventional smooth-walled clamp would not work with the recess.
The objective of the present invention is to provide a steel wheel, especially for an automotive vehicle, which presents solutions for the fixation of the wheel balance weight on the wheel flange so that the wheel can have any type of surface finish, even if this entails a reduced friction coefficient, and so that a conventional balance weight having a smooth-walled balance weight clamp can be securely affixed to the wheel flange.
It is also an objective of the present invention to provide a wheel rim and a wheel disc that present solutions for the fixation of the wheel weight independently of the friction coefficient presented by its surface, and so that a conventional balance weight having a smooth-walled balance weight clamp can be securely affixed to the wheel flange.
The objectives of the present invention are achieved by means of a wheel, especially for use on vehicles, comprising a peripheral wheel flange defining an end region that has a portion that extends generally radially outwardly and transitions into a further portion that extends generally axially up to a free end, a generally radially facing surface of the end region defining a fitting recess therein for engagement by at least one wheel balance weight. The recess defines a contact surface having a length extending away from the free end of the end region, the contact surface being configured to contact and frictionally engage a balance weight fixing clamp whose wall is free of locking projections or protuberances.
Preferably, the balance weight clamp contacts the contact surface of the recess along substantially the entire length of the contact surface. The substantial surface area contacted by the clamp thus provides increased frictional force.
Preferably, the cross-sectional shape of the recess (in the radial-axial plane) is substantially wedge-shaped. It is also preferred that the contact surface of the recess be substantially conical, which facilitates having substantially the entire length of the contact surface in contact with the clamp of the balance weight.
Also, the objectives of the present invention are achieved by means of a wheel rim, especially for use on a wheel designed for use on vehicles, comprising a peripheral flange as described above.
Further, the objectives of the present invention are achieved by means of a wheel disc, especially for use on a wheel designed for use on vehicles, comprising a peripheral flange as described above.
The wheel configured according to the teachings of the present invention has the advantage of enabling one to fix weights correctly for counterbalance, even in the case of a chromed finish, which is esthetically more attractive but has a quite smooth surface finish. The invention provides a wheel that presents the esthetics desired by the market, reduced manufacture cost, and efficiency in fixing weights for counterbalance.